Stacked display medium

ABSTRACT

A display medium including a layered structure that comprises two or more stacked display elements that each are provided, on or above a flexible substrate, with a pixel portion and lead line(s) for electrically connecting the pixel portion to outside of the pixel portion, and a hole portion or a cut-away portion included in the display element(s) that are above one or more of the lead line(s) of the display element(s) at a lower portion of the layered structure, so that the one or more of the lead line(s) of the lower portion display element(s) are exposed.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. 119 from JapanesePatent Application No. 2006-246869, the disclosure of which isincorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display medium, and more particularlyto a display medium including two or more display elements that havebeen stacked together.

2. Description of the Related Art

Display mediums from two or more display elements that have been stackedtogether have been proposed. At the external terminal connectionportions of such layered form display mediums, in order for the leadlines from the pixel portion (functional area) of the display elementsto be each individually connected to the outside of the pixel portion,patterns are adopted in which, for example, the end portions of thestacked display elements project out from each of the substrates, theend portions of the stacked display elements are disposed in a stepshape, or the like (see, for example, Japanese Patent Application (JP-A)Nos. 2001-42353, 2002-297050).

FIG. 16 is an example of a configuration of external terminal connectionportions in a conventional layered form display medium and is a partialcross-section showing schematically a display medium of three stackeddisplay elements (100 a, 100 b and 100 c). In FIG. 16, lead lines 102 a,102 b and 102 c are, respectively, formed to lead from display regions(not shown) in substrates 101 a, 101 b and 101 c in the display elements100 a, 100 b and 100 c, and external connection relay substrates 103 a,103 b and 103 c, for electrically connecting pixel portions to theoutside, are connected to the respective lead lines 102 a, 102 b and 102c. 104 a, 104 b and 104 c indicate protection films or cover glass. The104 a is disposed above the display element 100 a and protects thesurface of the display element 100 a. The 104 b and 104 c are disposedabove the display elements 100 b and 100 c, and protect the surfaces ofeach of the display elements and are also able to act as insulators.

However, in a conventional layered form display medium like the onedescribed above, there is the problem that the strength of the externalterminal connection portions thereof is low. That is to say, in aconventional layered form display medium, since there are end portionsof plural display elements stacked in a step shape, or since there arestacked end portions protruding out from each of the substrates, thestrength is low at the boundary portion at the end portion of thejoining portion(s) where an upper portion display element meets a lowerportion display element, and there is the problem that when bendingstress is applied to the joining end portion, the lead wiring lines thatare present at the boundary portion may break.

Furthermore, electrical connection, between such a display medium and arelay substrate for external connection, must be undertaken for each ofthe display elements configuring the display medium, and the same numberof relay substrates for external connection is required as the number ofstacked display elements, and the problem arises that the productionprocess thereof becomes complicated.

Recently, demand for display media that are flexible has risen, becauseof the ease of transporting and the portability of devices containingsuch display media. Such flexible display media usually use a flexiblesubstrate of the order of several tens of μm to several hundreds of μmin thickness as the substrate. There is particular demand with flexibledisplay media using flexible substrates for an increase in the strengthof the external terminal connection portions thereof, but the presentsituation is that there is nothing yet available that meets suchdemands.

SUMMARY OF THE INVENTION

The present invention has been made in consideration of theabove-described circumstances and provides a display medium with two ormore stacked display elements.

An aspect of the invention is to provide a display medium including alayered structure that comprises two or more stacked display elementsthat each are provided, on or above a flexible substrate, with a pixelportion and lead line(s) for electrically connecting the pixel portionto outside of the pixel portion, and a hole portion or a cut-awayportion included in the display element(s) that are above one or more ofthe lead line(s) of the display element(s) at a lower portion of thelayered structure, so that the one or more of the lead line(s) of thelower portion display element(s) are exposed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an outline configuration of adisplay medium according to an exemplary embodiment A of the presentinvention;

FIG. 2 is a plan view showing a partial enlargement of an end portion ofthe display medium according to the exemplary embodiment A of thepresent invention;

FIG. 3 is an end cross-section taken along A-A of FIG. 2;

FIG. 4A is an end cross-section taken along B-B of FIG. 2; FIG. 4B is anend cross-section taken along C-C of FIG. 2; and FIG. 4C is an endcross-section taken along D-D of FIG. 2;

FIG. 5 is an outline diagram showing connections between a displaymedium according to the present invention and a flexible substrate;

FIG. 6 is a plan view showing a partial enlargement of an end portion(external terminal connection portion) of a display medium according toa first example modification to the exemplary embodiment A of thepresent invention;

FIG. 7 is a top surface view showing an example of connections between adisplay medium according to the first example modification and anexternal connection substrate;

FIG. 8 is a plan view showing a partial enlargement of an end portion(external terminal connection portion) of a display medium according toa second example modification;

FIG. 9 is a plan view showing a partial enlargement of an end portion(external terminal connection portion) of a display medium according toa third example modification;

FIG. 10A is an end cross-section taken along E-E of FIG. 9; and FIG. 10Bis an end cross-section taken along F-F of FIG. 9;

FIG. 11 is a plan view showing a partial enlargement of an end portion(external terminal connection portion) of a display medium according toa fourth example modification;

FIG. 12 is a top surface view showing an example of connections betweena display medium according to the fourth example modification and anexternal connection substrate;

FIG. 13A is an end cross-section taken along G-G of FIG. 11; and FIG.13B is an end cross-section taken along H-H of FIG. 11;

FIG. 14 is a plan view showing schematically an example pixelarrangement in a pixel portion, and an example arrangement of lead linesthat leading from each of the pixels;

FIG. 15 is a plan view showing schematically an example pixelarrangement in a pixel portion, and an example arrangement of lead linesthat leading from each of the pixels; and

FIG. 16 is a partial cross-section showing a conventional example of adisplay medium.

BRIEF DESCRIPTION OF THE INVENTION

The present invention will be described in detail below.

The display medium of the present invention is a display mediumincluding a layered structure that includes two or more stacked displayelements that each are provided, on or above a flexible substrate, witha pixel portion and lead line(s) for electrically connecting the pixelportion to the outside of the pixel portion, and a hole portion or acut-away portion included in the display element(s) above one or more ofthe lead lines of the display element(s) at a lower portion of thelayered structure so that the one or more of the lead lines of the lowerportion display element(s) are exposed.

In the display medium of the present invention, by including the holeportion or the cut-away portion, the external terminal connectionportion is strong, and also, easy electrical connection may be made to arelay substrate for external connection, even if there are two or moreof the display elements that have been stacked. Specifically, in thedisplay medium of the present invention, by having the hole portion orthe cut-away portion such that the lead line(s) of a display elementthat is at a lower portion of the layered structure are exposed, sincethe thickness at the end portion may be maintained, even if a bendingstress is applied the force thereof is distributed over the whole of thedisplay medium, and so there is no concentration of the stress at aportion of the end portion of the stacked display element, thereforeenabling a display medium that has high strength to bending stress.Furthermore, in the display medium of the present invention, theelectrical connection from the two or more display elements to externalportion(s) does not use two or more relay substrates for externalconnection, and may be undertaken with a single relay substrate forexternal connection, therefore electrical connection from the externalterminal connection portions to external portion(s) becomes easy, andsimplification may be achieved in the manufacturing processes of thedisplay medium. Furthermore, in the present invention, since a flexiblesubstrate is used, the hole portion or the cut-away portion may beeasily formed.

The hole portion and the cut-away portion of the present invention arepreferably formed by forming the hole portion or the cut-away portion inthe display element(s) before stacking the display elements, followed bystacking the display elements. Description will be given later regardingproduction methods of the display medium of the present invention.

It is preferable that, in the display medium of the present invention,there are two or more of the hole portions or of the cut-away portions,and the two or more of the hole portions or of the cut-away portions arearranged in a row along a direction X, wherein the direction X is adirection that is along one of the edges of the display medium. When twoor more of the hole portions or of the cut-away portions are arrangedalong the direction X, between the two of more of the hole portions orthe cut-away portions and at the edge side of the display medium, ridgedportions are formed that is of the same thickness as that of the displaymedium, therefore, the strength at the external terminal connectionportion to bending stress or the like may be increased even further.

It is also preferable that, in the display medium of the presentinvention, there are two or more of the hole portions or of the cut-awayportions, and the two or more of the hole portions or of the cut-awayportions are arranged along a direction X and stepped in a direction Y,wherein the direction X is a direction that is along one of the edges ofthe display medium, and the direction Y is a direction that is along anedge of the display medium that is orthogonal to the direction X. Bythus arranging the two or more of the hole portions or of the cut-awayportions, portions are formed at peripheral portions to the two or moreof the hole portions or the cut-away portions that are of the samethickness as the middle portion of the display medium, thereby thestrength of the external terminal connection portion of the displaymedium may be increased even further.

It is preferable, in the display medium of the present invention, toarrange the respective lead lines of each of the two or more stackeddisplay elements so that they are superimposed in the display elementstacking direction.

Or, it is preferable in the display medium of the present invention, toarrange the respective lead lines of each of the two or more stackeddisplay elements so that they are parallel to each other in a directionthat is orthogonal to the display element stacking direction.

It is preferable, in the display medium of the present invention, tohave two or more of the lead lines exposed through a single hole portionor cut-away portion. By having the hole portion or the cut-away portionprovided to the display element(s), such that the lead line(s) of thedisplay element(s) that are at a lower portion of the layered structureare exposed, the degrees of freedom in wiring layout of the lead linesmay be increased.

It is preferable, in the display medium of the present invention, tofurther include a protective layer provided on or above a displayelement located at an upper portion of the layered structure, theprotective layer including a hole portion or a cut-away portion providedsuch that one or more of the lead lines are exposed. By providing theprotective layer on or above the display element located at an upperportion of the layered structure, the occurrence of externally causedscratches or the like may be avoided.

In the display medium of the present invention, two or more displayelements that are different color s from each other may be included.When, in the present invention, two or more display elements that aredifferent color s from each other are stacked, the aperture area of eachof the pixels in a single one of the display elements may be made large,and so the light emitting efficiency of each of the display elements maybe increased.

It is preferable in the display medium of the present invention that thepixel portion is a pixel portion that uses organic electroluminescence.

It is preferable in the display medium of the present invention that thetwo or more display elements are stacked with a adhesive layertherebetween that is formed to cover the whole of the surface betweenthe display elements. By having a adhesive layer, color misalignmentarising due to the bending of the display elements may be prevented.

Detailed explanation will now be given of exemplary embodiments of thedisplay medium of the present invention, with reference to FIGS. 1 to 13that show a first example modification to a fourth example modificationof an exemplary embodiment A. However the present invention is notlimited to the following exemplary embodiment or example modificationsthereof.

FIG. 1 is a perspective view showing an outline configuration of adisplay medium 10 that is the exemplary embodiment A of the displaymedium of the present invention. In FIGS. 1, 11 a, 11 b and 11 c aredisplay elements, and display medium 10 has a layered structure of atriple layer of the display elements 11 a, 11 b, and 11 c, and at an endportion thereof (an external terminal connection portion) there areplural hole portions 15A provided that are a feature of the presentinvention.

In the present exemplary embodiment the hole portions 15A are providedat a single end portion of the display medium 10, however, depending onthe wiring layout pattern of the lead lines, the hole portions 15A mayalso be provided at another end portion.

The display element 11 a is provided, on a flexible substrate 12 a, witha pixel portion 13 a, and lead lines 14 a for electrically connectingthe pixel portion 13 a to outside of the pixel portion. Details of thedisplay element 11 b and the display element 11 c are not show in FIG.1, however, similar to display element 11 a, they are each configuredwith, on a flexible substrate, respective pixel portions 13 b and 13 c,and lead lines 14 b and 14 c for electrically connecting the pixelportions to outside of the pixel portions.

FIG. 2, is a plan view of a partial enlargement of an end portion(external terminal connection portion) of the display medium 10. FIG. 3is an end cross-section taken along A-A of FIG. 2; FIGS. 4A to 4C areend cross-sections taken, respectively, along B-B, C-C, and D-D of FIG.2.

As shown in FIG. 1 to FIG. 4, in the display medium 10, the lead lines14 a, 14 b and 14 c respectively formed on the flexible substrates 12 a,12 b and 12 c are arranged so as to be superimposed on each other in thestacking direction of the display medium 10, and hole portions 15A areprovided, of a depth corresponding to that at which each of the leadlines is formed, in the display element above the lead lines 14 b and 14c that are located at positions at a lower portion of the layeredstructure, such that both the lead lines 14 b and 14 c are exposed. Thelead lines 14 a formed on the flexible substrate 12 a, and the leadlines 14 b and 14 c exposed at the hole portions 15A are exposed in astep form when moving along the same straight line (in direction Y inFIG. 2).

Here, “at positions at a lower portion of the layered structure” meanspositions to the side of the flexible substrates relative to itsrespective stacked display elements.

In this manner, by exposing both of the lead lines 14 b and 14 c throughthe hole portions 15A, when electrically connecting the display elements11 a, 11 b and 11 c to a relay substrate for external connection and toexternal portions, a relay substrate for external connection for each ofthe display elements is not required, and a single relay substrate forexternal connection may be used.

At the hole portions 15A side of the display medium 10 there is a ridgeportion 17 formed (see FIG. 3), and between the plural hole portions 15Athat exist there are ridge portions 18 formed (see FIGS. 4B and 4C).Since the ridge portion 17 and the ridge portions 18 have the samethickness as that of the display medium 10, therefore the end portion(external terminal connection portion) of the display medium 10 is ofexcellent strength.

The display elements 11 a, 11 b and 11 c configuring the display medium10 are stacked with the adhesive layers 16 a and 16 b therebetween. Theadhesive layers 16 a and 16 b are preferably formed to cover the wholeof the surface between the display elements 11 a and 11 b, and 11 b and11 c, but may be formed only on a partial region thereof.

The relay substrate for external connection connected to the displaymedium 10 is preferably a flexible substrate and, for example, a FPC(Flexible Printed Circuit) or the like, may be used.

The ridge portion 17 and the ridge portions 18, when the displayelements and flexible substrate are connected through an ACF(Anisotropic Conductive Film) by thermo-compression bonding or the like,the ridge portion 17 and ridge portions 18 are buried within theflexible substrate, and so may also perform a so-called wedge function,fixing more firmly the connected display elements and the relaysubstrate for external connection.

FIG. 5 shows a cross-section of the state of an external connectionrelay substrate 50 connected to the external terminal connection portionof a display medium 10. The external connection relay substrate 50 isconfigured with a base 51 made from a flexible material, externalconnection relay lines 52 disposed on the base 51, and an ACF 53 that isdisposed on the terminal portion of the external connection relay lines52 so as to be connected thereto. An end portion of the externalconnection relay substrate 50 and the external terminal connectionportion of the display medium 10 are connected together bythermo-compression bonding or the like, and the exposed portions of leadlines 14 a, 14 b and 14 c of the display medium 10 are in contact withthe ACF 53 of the external connection relay substrate 50, and thedisplay medium 10 is electrically connected to external portions throughthe external connection relay substrate 50.

Explanation will now be given of the first to the fourth examplemodifications, which are example modifications of the exemplaryembodiment A.

FIRST EXAMPLE MODIFICATION

FIG. 6 is a plan view of a partial enlargement of an end portion(external terminal connection portion) of the display medium accordingto the first example modification. In the first example modification theconfiguration is basically the same as that of the display medium 10 ofthe exemplary embodiment A, but instead of the above described holeportions 15A, there are cut-away portions 15B.

Since elements of the configuration of the first example modification,other than the cut-away portions 15B, are similar to those of theexemplary embodiment A, the same reference numerals are used.

FIG. 7 is a top surface view showing an example of connections between adisplay medium according to the first example modification and anexternal connection substrate 60, and shows in the first examplemodification a connection state in which the lead lines 14 a, 14 b and14 c that are exposed to the outside are connected, respectively, toexternal connection relay lines 62 a, 62 b, and 62 c that are disposedon a single base 61 configuring a substrate for external connection.

SECOND EXAMPLE MODIFICATION

FIG. 8 is a plan view showing a partial enlargement of an end portion(external terminal connection portion) of a display medium according toa second example modification. In the second example modification theconfiguration is basically the same as that of the display medium 10 ofthe exemplary embodiment A, but instead of the above described holeportions 15A, there is/are hole portion(s) 15C. The hole portions 15Care a form in which plural hole portions 15A have been made common, andplural lead lines that are arranged parallel to each other in adirection that is orthogonal to the stacking direction of the displayelements (a group of lead lines 14 a, 14 b or 14 c for example) areexposed through a single hole portion 15C.

Since elements of the configuration of the second example modification,other than the hole portions 15C, are similar to those of the exemplaryembodiment A, the same reference numerals are used.

THIRD EXAMPLE MODIFICATION

FIG. 9 is a plan view showing a partial enlargement of an end portion(external terminal connection portion) of a display medium according toa third example modification. FIG. 10A and FIG. 10B are endcross-sections taken respectively along E-E and F-F of FIG. 9.

In the third example modification the configuration is basically thesame as that of the display medium 10 of the exemplary embodiment A, buthole portions 15D arranged along a direction X and stepped in adirection Y, wherein the direction X is a direction that is along one ofthe edges of the display medium, and the direction Y is a direction thatis along an edge of the display medium that is orthogonal to thedirection X.

Since elements of the configuration of the third example modification,other than the hole portions 15D, are similar to those of the exemplaryembodiment A, the same reference numerals are used.

By arranging the hole portions 15D stepped in this manner, the strengthof the external terminal connection portions of the display medium maybe further increased.

The present example modification, as shown in FIG. 9 and FIG. 10, hasexposed through a single hole portion one or other of the lead lines 14b or the lead lines 14 c, however both the lead lines 14 b and 14 c maybe exposed through the same hole portion 15D, similar to in theexemplary embodiment A.

FOURTH EXAMPLE MODIFICATION

FIG. 11 is a plan view showing a partial enlargement of an end portion(external terminal connection portion) of a display medium according toa fourth example modification.

FIG. 12 is a top surface view showing an example of connections betweena display medium according to the fourth example modification and anexternal connection substrate 70, showing a connection state in whichthe lead lines 14 a, 14 b and 14 c that are exposed to the outside inthe fourth example modification are respectively connected to pluralexternal connection relay lines 72 that are disposed on a single base 71configuring a substrate for external connection.

FIG. 13A and FIG. 13B are end cross-sections taken respectively alongG-G and H-H of FIG. 11.

In the fourth example modification the configuration is basically thesame as that of the display medium 10 of the exemplary embodiment A, butlead lines 14 a and 14 b are arranged rowed in a direction (direction X)that is along one of the edges of the display medium and arranged inparallel to each other in a direction that is orthogonal to the stackingdirection of the display elements, and are exposed through a single holeportion 15E.

The fourth example modification has a protective layer 20, provided onthe display elements at a location at an upper portion of the layeredstructure, with hole portions or cut-away portions therein so as toexpose the lead lines 14 a, 14 b and 14 c.

It is preferable that a protective layer is also provided to the aboveexemplary embodiment A and the first to the fourth examplemodifications.

Since elements of the configuration of the fourth example modification,other than the hole portion 15E and the protective layer 20, are similarto those of the exemplary embodiment A, the same reference numerals areused.

Further explanation will now be given of common elements of the displaymedium of the present invention explained in the exemplary embodiment Aand the first to the fourth example modifications thereof.

Flexible Substrate

A base plate of a polymer film or the like may be used as the flexiblesubstrate of the display medium. Examples that may be given thereofinclude, for example, PEN, PC, PET and the like.

Particulars Relating to the Pixel Portions and the Lead Lines

The pixel portion of the display medium of the present invention includeat least one pixel, and there are lead lines leading from the electrodesof the pixel(s). The pixels of each of the display elements may besuperimposed in the stacking direction of the display medium, or may bearranged so as to be parallel to each other in a direction that isorthogonal to the stacking direction of each of the display elements.

FIG. 14 and FIG. 15 are plan views showing schematically examples ofpixel arrangements in the pixel portion, and example arrangements oflead lines leading from each of the pixels.

FIG. 14 shows a pattern in which pixels 30 a, 30 b and 30 c on thedisplay elements are superimposed in the stacking direction, shows leadlines 32 a, 32 b and 32 c leading out in the column direction, and showslead lines 34 a, 34 b and 34 c leading out in the row direction. Thepixels 30 a, 30 b and 30 c are each formed on different flexiblesubstrates.

FIG. 15 shows a pattern in which pixels on the each of the displayelements (40 a, 40 b and 40 c) are arranged so as to be parallel to eachother in a direction that is orthogonal to the stacking direction, showslead lines 42 a, 42 b and 42 c leading out in the column direction, andshows lead lines 44 a, 44 b and 44 c leading out in the row direction.The pixels 40 a, 40 b and 40 c are each formed on different flexiblesubstrates.

As shown in FIGS. 14 and 15, the arrangement patterns of each of thelead line end portions may take up: a pattern in which they aresuperimposed vertically in the stacking direction of the display medium(portions shown by (I) in FIGS. 14 and 15); a pattern in which they arerowed in a single row parallel to each other along a direction that isorthogonal to the stacking direction of the display medium (portionsshown by (II) in FIGS. 14 and 15); or a pattern in which they are rowedin a step-like pattern along a direction that is parallel to thestacking direction of the display medium (portions shown by (III) inFIGS. 14 and 15). The above exemplary embodiment A and the first to thefourth example modifications thereof may take any of the above patterns(I) to (III).

Any one of the above patterns (I) to (III), or combinations thereof, maybe applied to the arrangement pattern of the lead line end portions inthe display medium of the present invention.

In the present invention, by configuring each of the display elementswith respectively different colors for the pixel portion of each of thedisplay elements configuring the layered structure, the display mediumof the present invention may be made multi-color display compatible.

Pixels displaying organic electroluminescence or inorganicelectroluminescence may be used for the pixel portion.

There are no particular limitations to the pixels displaying organicelectroluminescence for the pixel portion, and they may be formedaccording to the application. For example, when forming pixelsdisplaying organic electroluminescence using low molecular weight basedmaterials, a transparent anode first electrode of ITO or the like may beformed on a flexible substrate, then after cleaning, an organic layersuch as a light-emitting layer may be formed as a film by vacuumdeposition. Next, a second electrode of ITO or the like may be formed bysputtering. When forming pixels of an organic EL element using highmolecular weight based materials, after forming an organic layer, thistime using a coating method, a printing method, a spin coating method,an inkjet method or the like, a second electrode of ITO or the like maybe formed by sputtering. A layered multi photon emission element may beformed with a series of light emitting layers or the like.

Adhesive Layer

The adhesive layer may be made, for example, using double-sided tape orthermosetting resin or the like.

Protective Layer

A protective layer that is applicable to the present invention is onewhich is formed on or above a display element located at an upperportion of the layered structure, and has hole portions or cut-awayportions therein so as to expose the lead lines. PEN, PC, PET and thelike may, for example, be used for the protective layer. The holeportions or cut-away portions of the protective layer may be provided bypunching out using a mold.

Production Method of the Display Medium

The display medium of the present invention may be manufactured, forexample, in the following manner.

A transparent conducting film of an ITO layer of 100 nm thickness isformed as a film on PEN that is to form the flexible substrate. Next, astriped pattern is formed thereon of photoresist using aphotolithographic method, and a striped first electrode obtained throughetching and peeling processes.

Next plural organic layers are formed in sequence through apredetermined vapor deposition mask by a vacuum deposition method,forming an EL layer. Here, “plural organic layers” indicates holeinjection layer(s), hole transport layer(s), light emitting layer(s),electron transport layer(s), electron injection layer(s) and the like,and each of the respective layers is selected of a suitable organicmaterial to correspond with the particular desired light emitting color,such as red, green, or blue.

Next, as a second electrode, an Al film, an Ag film, and an ITO film areformed with respective thicknesses of 1.5 nm, 15 nm and 100 nm by vacuumdeposition, sputtering, using a striped film forming mask so that thesecond electrode is orthogonal to the first electrode. By doing so theintersecting portions of the first electrode and the second electrodemay emit light, and plural pixel portions are provided.

Next, a sealing film is formed so as to cover the light emittingelements. The sealing film may be formed by a CVD method, for example soas to form a film of SiON of 5 μm.

Three display element sheets of red, green and blue may be produced inthe above manner. Then, in order to adhere together the three displayelement sheets and the protective layer film in the sequence red, green,blue, protective layer film, a adhesive layer (Trade name: HJ-9150W;manufactured by Nitto Denko Corporation) is stuck to the reverse face ofeach of the green, blue and protective layer films, so as to cover theentire surfaces thereof.

Next, hole portions are provided in predetermined positions in each ofthe adhesive layers using a hole forming mold, such that the positionsof the red, green and blue lead lines are exposed to the top of theprotective layer, the positions of the green and

lead lines are exposed to the top of the blue display element, and thepositions of the

lead lines are exposed to the top of the green display element.

Next each of the red, green and blue display elements are aligned andstuck together so as to be superimposed on each other, and the displaymedium is completed.

In response to the problem when lead lines are provided in a step formof lead lines severing due to concentration of load on the weakestportions, the display medium of the present invention has hole portionsor cut-away portions only at the lead line portions, and so there is noconcentration of stress at a single point when the display medium isbent, and severing of the lead lines may be prevented.

The display medium produced in the above manner is stacked in thesequence red, green, blue, however, the stacking sequence may be changesas desired to green, blue and red. Furthermore, the since the firstelectrode and the second electrode are formed from ITO, which is atransparent conducting film, light emission from both sides is possible,however, the first electrode of the display element that becomes thebottommost layer, or the second electrode of the display element thatbecomes the uppermost layer, may be formed using a non-transparentmaterial such as Al, and due to the high reflectivity thereof, a singleside light emitting display medium may be made.

As described above, according to the present invention, the strength ofthe external terminal connection portion is high, and, even if there aretwo or more stacked display elements, a display medium may be providedthat is easy to electrically connect to a relay substrate for externalconnection.

The display medium of the present invention is suitably applied toimproving the strength of lead line portions when different displayelements are stacked together.

All publications, patent applications, and technical standards mentionedin this specification are herein incorporated by reference to the sameextent as if each individual publication, patent application, ortechnical standard was specifically and individually indicated to beincorporated by reference.

1. A display medium comprising: a layered structure that comprises twoor more stacked display elements that each are provided, on or above aflexible substrate, with a pixel portion and lead line(s) forelectrically connecting the pixel portion to outside of the pixelportion; and a hole portion or a cut-away portion included in thedisplay element(s) that are above one or more of the lead line(s) of thedisplay element(s) at a lower portion of the layered structure, so thatthe one or more of the lead line(s) of the lower portion displayelement(s) are exposed, wherein each of the stacked display elementscomprises electrodes that are electrically independent from each otherstacked display element.
 2. The display medium according to claim 1,wherein there are two or more of the hole portions or of the cut-awayportions, and the two or more of the hole portions or of the cut-awayportions are arranged in a row along a direction X, wherein thedirection X is a direction that is along one of the edges of the displaymedium.
 3. The display medium according to claim 1, wherein there aretwo or more of the hole portions or of the cut-away portions, and thetwo or more of the hole portions or of the cut-away portions arearranged along a direction X and stepped in a direction Y, wherein thedirection X is a direction that is along one of the edges of the displaymedium, and the direction Y is a direction that is along an edge of thedisplay medium that is orthogonal to the direction X.
 4. The displaymedium according to claim 1, wherein the respective lead lines of eachof the two or more stacked display elements are arranged so that theyare superimposed in the display element stacking direction.
 5. Thedisplay medium according to claim 1, wherein the respective lead linesof each of the two or more stacked display elements are arranged so thatthey are parallel to each other in a direction that is orthogonal to thedisplay element stacking direction.
 6. The display medium according toclaim 1, wherein two or more of the lead lines are exposed through asingle hole portion or cut-away portion.
 7. The display medium accordingto claim 1, further comprising a protective layer provided on or abovethe display element located at an upper portion of the layeredstructure, the protective layer including a hole portion or a cut-awayportion provided such that one or more of the lead lines are exposed. 8.The display medium according to claim 1, wherein the stacked displayelements include two or more display elements that are different colorsfrom each other.
 9. The display medium according to claim 1, wherein thepixel portion include pixel portion that use organicelectroluminescence.
 10. The display medium according to claim 1,wherein the two or more display elements are stacked with a adhesivelayer therebetween that is formed to cover the whole of the surfacebetween the display elements.